Rectangular Bifilar Coil for Force Measuring System Stability
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Solution Overview
Problem
Force measuring systems with electromagnetic force compensation face issues due to load-dependent power losses and temperature fluctuations, leading to instability and reduced sensitivity, especially in compact designs with high resolution requirements, where bifilar winding coils are prone to leakage currents and reduced efficiency due to gaps and uneven insulation stress.
Innovation Solution
A multi-layer electromagnetic coil with a bifilar winding of winding wires having a substantially rectangular cross-sectional area is used, which minimizes gaps and uneven insulation stress, enhancing the degree of filling and reducing leakage currents, and simplifies the manufacturing process by allowing a more regular and symmetrical arrangement of turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bifilar winding coil is used for electromagnetic force compensation, then temperature compensation is achieved through opposing force components, but leakage currents occur due to gaps and uneven insulation stress, reducing efficiency
Solution Approach 1:
The patent changes the geometric parameters of the winding wire from circular to rectangular cross-section. This parameter change allows the wires to pack more tightly in the bifilar winding, eliminating gaps between adjacent turns. The rectangular cross-section with dimensions approximately 0.2-0.5mm x 0.05-0.2mm provides better contact area and more uniform distribution of mechanical and electrical stress across the insulation layer, preventing leakage currents while maintaining temperature compensation functionality.
Solution Approach 2:
The patent applies local quality by ensuring uniform insulation thickness specifically at the contact points between adjacent rectangular winding wires. The insulation layer is designed with locally enhanced properties at critical stress points, creating a more uniform electric field distribution and preventing localized breakdown that would lead to leakage currents.
2Volume of moving object
If the coil is designed for high resolution and compact size, then space utilization is maximized, but temperature differences at the lever influence sensitivity and reduce measurement accuracy
Solution Approach 1:
The patent utilizes the bifilar winding configuration with rectangular cross-section to achieve superior thermal management in a compact volume. The opposing current flow in the two wires of the bifilar structure generates equal and opposite heat effects, effectively canceling temperature differences. This allows the coil to be placed in compact spaces close to the lever without introducing harmful thermal gradients that would affect measurement sensitivity.
3Ease of manufacture
If conventional circular winding wires are used, then manufacturing is simpler, but gaps between turns reduce the degree of filling and increase leakage currents
Solution Approach 1:
The patent changes the cross-sectional shape parameter from circular to rectangular, which fundamentally improves the packing efficiency in bifilar windings. The rectangular wires with optimized aspect ratios can be tightly packed with minimal gaps between adjacent turns, achieving a degree of filling significantly higher than conventional circular wires. This geometric parameter change transforms the winding structure to eliminate the gaps that cause leakage currents.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design improves the stability and efficiency of the force measuring system by reducing temperature fluctuations and enhancing the degree of filling, leading to improved accuracy and reduced environmental influence, while simplifying the manufacturing process and maintaining long-term stability.
Implementation Method 1
The electromagnetic coil thus generates a counterforce which counteracts the transmitted force and which is referred to as a compensating force. The measuring principle is called electromagnetic force compensation.
Implementation Method 2
The force acting on the coil via the lever mechanism causes a change in the position of the coil, which is detected by a position sensor
Implementation Method 3
The magnetic field is generated using a permanent magnet with an air gap, with the coil immersed in the magnetic field in the air gap.
Data Source
Figure 1~2c
Figure 3a~4d
Figure 5a~5c
AI summary
The multi-layered electromagnetic coil has a multifilar wiring arrangement of coil wires, where each coil wire in the arrangement has a rectangular cross-sectional profile. The cross-sectional profile is a rounded rectangular shape, with the shorter sides being formed in a biconvex shape and the longer sides being flattened. An independent claim is also included for a method for manufacturing a coil.